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/* ptrace.c */

/* By Ross Biro 1/23/92 */

/* edited by Linus Torvalds */

#include <linux/config.h> /* CONFIG_MATH_EMULATION */

#include <linux/head.h>

#include <linux/kernel.h>

#include <linux/sched.h>

#include <linux/mm.h>

#include <linux/errno.h>

#include <linux/ptrace.h>

#include <linux/user.h>

#include <linux/debugreg.h>

#include <asm/segment.h>

#include <asm/pgtable.h>

#include <asm/system.h>

/*

 * does not yet catch signals sent when the child dies.

 * in exit.c or in signal.c.

 */

/* determines which flags the user has access to. */

/* 1 = access 0 = no access */

#define FLAG_MASK 0x00044dd5

/* set's the trap flag. */

#define TRAP_FLAG 0x100

/*

 * this is the number to subtract from the top of the stack. To find

 * the local frame.

 */

#define MAGICNUMBER 68

/* change a pid into a task struct. */

static inline struct task_struct * get_task(int pid)

{

        int i;

        for (i = 1; i < NR_TASKS; i++) {

                if (task[i] != NULL && (task[i]->pid == pid))

                        return task[i];

        }

        return NULL;

}

/*

 * this routine will get a word off of the processes privileged stack.

 * the offset is how far from the base addr as stored in the TSS.

 * this routine assumes that all the privileged stacks are in our

 * data space.

 */

static inline int get_stack_long(struct task_struct *task, int offset)

{

        unsigned char *stack;

        stack = (unsigned char *)task->tss.esp0;

        stack += offset;

        return (*((int *)stack));

}

/*

 * this routine will put a word on the processes privileged stack.

 * the offset is how far from the base addr as stored in the TSS.

 * this routine assumes that all the privileged stacks are in our

 * data space.

 */

static inline int put_stack_long(struct task_struct *task, int offset,

        unsigned long data)

{

        unsigned char * stack;

        stack = (unsigned char *) task->tss.esp0;

        stack += offset;

        *(unsigned long *) stack = data;

        return 0;

}

/*

 * This routine gets a long from any process space by following the page

 * tables. NOTE! You should check that the long isn't on a page boundary,

 * and that it is in the task area before calling this: this routine does

 * no checking.

 */

static unsigned long get_long(struct task_struct * tsk,

        struct vm_area_struct * vma, unsigned long addr)

{

        pgd_t * pgdir;

        pmd_t * pgmiddle;

        pte_t * pgtable;

        unsigned long page;

repeat:

        pgdir = pgd_offset(vma->vm_mm, addr);

        if (pgd_none(*pgdir)) {

                do_no_page(tsk, vma, addr, 0);

                goto repeat;

        }

        if (pgd_bad(*pgdir)) {

                printk("ptrace: bad page directory %08lx\n", pgd_val(*pgdir));

                pgd_clear(pgdir);

                return 0;

        }

        pgmiddle = pmd_offset(pgdir, addr);

        if (pmd_none(*pgmiddle)) {

                do_no_page(tsk, vma, addr, 0);

                goto repeat;

        }

        if (pmd_bad(*pgmiddle)) {

                printk("ptrace: bad page middle %08lx\n", pmd_val(*pgmiddle));

                pmd_clear(pgmiddle);

                return 0;

        }

        pgtable = pte_offset(pgmiddle, addr);

        if (!pte_present(*pgtable)) {

                do_no_page(tsk, vma, addr, 0);

                goto repeat;

        }

        page = pte_page(*pgtable);

/* this is a hack for non-kernel-mapped video buffers and similar */

        if (page >= high_memory)

                return 0;

        page += addr & ~PAGE_MASK;

        return *(unsigned long *) page;

}

/*

 * This routine puts a long into any process space by following the page

 * tables. NOTE! You should check that the long isn't on a page boundary,

 * and that it is in the task area before calling this: this routine does

 * no checking.

 *

 * Now keeps R/W state of page so that a text page stays readonly

 * even if a debugger scribbles breakpoints into it.  -M.U-

 */

static void put_long(struct task_struct * tsk, struct vm_area_struct * vma, unsigned long addr,

        unsigned long data)

{

        pgd_t *pgdir;

        pmd_t *pgmiddle;

        pte_t *pgtable;

        unsigned long page;

repeat:

        pgdir = pgd_offset(vma->vm_mm, addr);

        if (!pgd_present(*pgdir)) {

                do_no_page(tsk, vma, addr, 1);

                goto repeat;

        }

        if (pgd_bad(*pgdir)) {

                printk("ptrace: bad page directory %08lx\n", pgd_val(*pgdir));

                pgd_clear(pgdir);

                return;

        }

        pgmiddle = pmd_offset(pgdir, addr);

        if (pmd_none(*pgmiddle)) {

                do_no_page(tsk, vma, addr, 1);

                goto repeat;

        }

        if (pmd_bad(*pgmiddle)) {

                printk("ptrace: bad page middle %08lx\n", pmd_val(*pgmiddle));

                pmd_clear(pgmiddle);

                return;

        }

        pgtable = pte_offset(pgmiddle, addr);

        if (!pte_present(*pgtable)) {

                do_no_page(tsk, vma, addr, 1);

                goto repeat;

        }

        page = pte_page(*pgtable);

        if (!pte_write(*pgtable)) {

                do_wp_page(tsk, vma, addr, 1);

                goto repeat;

        }

/* this is a hack for non-kernel-mapped video buffers and similar */

        if (page < high_memory)

                *(unsigned long *) (page + (addr & ~PAGE_MASK)) = data;

/* we're bypassing pagetables, so we have to set the dirty bit ourselves */

/* this should also re-instate whatever read-only mode there was before */

        set_pte(pgtable, pte_mkdirty(mk_pte(page, vma->vm_page_prot)));

        flush_tlb();

}

static struct vm_area_struct * find_extend_vma(struct task_struct * tsk, unsigned long addr)

{

        struct vm_area_struct * vma;

        addr &= PAGE_MASK;

        vma = find_vma(tsk->mm,addr);

        if (!vma)

                return NULL;

        if (vma->vm_start <= addr)

                return vma;

        if (!(vma->vm_flags & VM_GROWSDOWN))

                return NULL;

        if (vma->vm_end - addr > tsk->rlim[RLIMIT_STACK].rlim_cur)

                return NULL;

        vma->vm_offset -= vma->vm_start - addr;

        vma->vm_start = addr;

        return vma;

}

/*

 * This routine checks the page boundaries, and that the offset is

 * within the task area. It then calls get_long() to read a long.

 */

static int read_long(struct task_struct * tsk, unsigned long addr,

        unsigned long * result)

{

        struct vm_area_struct * vma = find_extend_vma(tsk, addr);

        if (!vma)

                return -EIO;

        if ((addr & ~PAGE_MASK) > PAGE_SIZE-sizeof(long)) {

                unsigned long low,high;

                struct vm_area_struct * vma_high = vma;

                if (addr + sizeof(long) >= vma->vm_end) {

                        vma_high = vma->vm_next;

                        if (!vma_high || vma_high->vm_start != vma->vm_end)

                                return -EIO;

                }

                low = get_long(tsk, vma, addr & ~(sizeof(long)-1));

                high = get_long(tsk, vma_high, (addr+sizeof(long)) & ~(sizeof(long)-1));

                switch (addr & (sizeof(long)-1)) {

                        case 1:

                                low >>= 8;

                                low |= high << 24;

                                break;

                        case 2:

                                low >>= 16;

                                low |= high << 16;

                                break;

                        case 3:

                                low >>= 24;

                                low |= high << 8;

                                break;

                }

                *result = low;

        } else

                *result = get_long(tsk, vma, addr);

        return 0;

}

/*

 * This routine checks the page boundaries, and that the offset is

 * within the task area. It then calls put_long() to write a long.

 */

static int write_long(struct task_struct * tsk, unsigned long addr,

        unsigned long data)

{

        struct vm_area_struct * vma = find_extend_vma(tsk, addr);

        if (!vma)

                return -EIO;

        if ((addr & ~PAGE_MASK) > PAGE_SIZE-sizeof(long)) {

                unsigned long low,high;

                struct vm_area_struct * vma_high = vma;

                if (addr + sizeof(long) >= vma->vm_end) {

                        vma_high = vma->vm_next;

                        if (!vma_high || vma_high->vm_start != vma->vm_end)

                                return -EIO;

                }

                low = get_long(tsk, vma, addr & ~(sizeof(long)-1));

                high = get_long(tsk, vma_high, (addr+sizeof(long)) & ~(sizeof(long)-1));

                switch (addr & (sizeof(long)-1)) {

                        case 0: /* shouldn't happen, but safety first */

                                low = data;

                                break;

                        case 1:

                                low &= 0x000000ff;

                                low |= data << 8;

                                high &= ~0xff;

                                high |= data >> 24;

                                break;

                        case 2:

                                low &= 0x0000ffff;

                                low |= data << 16;

                                high &= ~0xffff;

                                high |= data >> 16;

                                break;

                        case 3:

                                low &= 0x00ffffff;

                                low |= data << 24;

                                high &= ~0xffffff;

                                high |= data >> 8;

                                break;

                }

                put_long(tsk, vma, addr & ~(sizeof(long)-1),low);

                put_long(tsk, vma_high, (addr+sizeof(long)) & ~(sizeof(long)-1),high);

        } else

                put_long(tsk, vma, addr, data);

        return 0;

}

#ifdef CONFIG_MATH_EMULATION

static void write_emulator_word(struct task_struct *child,

                                unsigned long register_offset,

                                long data)

{

        int i, j;

        struct i387_soft_struct *soft_fpu;

        struct fpu_reg *this_fpreg, *next_fpreg;

        char hard_reg[2][10];

        int control_word;

        unsigned long top;

        i = register_offset / 10;

        j = register_offset % 10;

        soft_fpu = &child->tss.i387.soft;

        top = i + (unsigned long) soft_fpu->top;

        control_word = soft_fpu->cwd;

        this_fpreg = &soft_fpu->regs[(top + i) % 8];

        next_fpreg = &soft_fpu->regs[(top + i + 1) % 8];

        softreg_to_hardreg(this_fpreg, hard_reg[0], control_word);

        if (j > 6)

                softreg_to_hardreg(next_fpreg, hard_reg[1], control_word);

        *(long *) &hard_reg[0][j] = data;

        hardreg_to_softreg(hard_reg[0], this_fpreg);

        if (j > 6)

                hardreg_to_softreg(hard_reg[1], next_fpreg);

}

#endif /* defined(CONFIG_MATH_EMULATION) */

/*

 * Floating point support added to ptrace by Ramon Garcia,

 * ramon@juguete.quim.ucm.es

 */

#ifdef CONFIG_MATH_EMULATION

static unsigned long get_emulator_word(struct task_struct *child,

                                       unsigned long register_offset)

{

        char hard_reg[2][10];

        int i, j;

        struct fpu_reg *this_fpreg, *next_fpreg;

        struct i387_soft_struct *soft_fpu;

        long int control_word;

        unsigned long top;

        unsigned long tmp;

        i = register_offset / 10;

        j = register_offset % 10;

        soft_fpu = &child->tss.i387.soft;

        top = (unsigned long) soft_fpu->top;

        this_fpreg = &soft_fpu->regs[(top + i) % 8];

        next_fpreg = &soft_fpu->regs[(top + i + 1) % 8];

        control_word = soft_fpu->cwd;

        softreg_to_hardreg(this_fpreg, hard_reg[0], control_word);

        if (j > 6)

                softreg_to_hardreg(next_fpreg, hard_reg[1], control_word);

        tmp = *(long *)

                &hard_reg[0][j];

        return tmp;

}

#endif /* defined(CONFIG_MATH_EMULATION) */

static int putreg(struct task_struct *child,

        unsigned long regno, unsigned long value)

{

        switch (regno >> 2) {

                case ORIG_EAX:

                        return -EIO;

                case FS:

                case GS:

                case DS:

                case ES:

                        if (value && (value & 3) != 3)

                                return -EIO;

                        value &= 0xffff;

                        break;

                case SS:

                case CS:

                        if ((value & 3) != 3)

                                return -EIO;

                        value &= 0xffff;

                        break;

                case EFL:

                        value &= FLAG_MASK;

                        value |= get_stack_long(child, sizeof(long)*EFL-MAGICNUMBER) & ~FLAG_MASK;

        }

        put_stack_long(child, regno - sizeof(struct pt_regs), value);

        return 0;

}

static unsigned long getreg(struct task_struct *child,

        unsigned long regno)

{

        unsigned long retval = ~0UL;

        switch (regno >> 2) {

                case FS:

                case GS:

                case DS:

                case ES:

                case SS:

                case CS:

                        retval = 0xffff;

                        /* fall through */

                default:

                        regno = regno - sizeof(struct pt_regs);

                        retval &= get_stack_long(child, regno);

        }

        return retval;

}

asmlinkage int sys_ptrace(long request, long pid, long addr, long data)

{

        struct task_struct *child;

        struct user * dummy;

        int i;

        dummy = NULL;

        if (request == PTRACE_TRACEME) {

                /* are we already being traced? */

                if (current->flags & PF_PTRACED)

                        return -EPERM;

                /* set the ptrace bit in the process flags. */

                current->flags |= PF_PTRACED;

                return 0;

        }

        if (pid == 1)           /* you may not mess with init */

                return -EPERM;

        if (!(child = get_task(pid)))

                return -ESRCH;

        if (request == PTRACE_ATTACH) {

                if (child == current)

                        return -EPERM;

                if ((!child->dumpable ||

                    (current->uid != child->euid) ||

                    (current->uid != child->suid) ||

                    (current->uid != child->uid) ||

                    (current->gid != child->egid) ||

                    (current->gid != child->sgid) ||

                    (current->gid != child->gid)) && !suser())

                        return -EPERM;

                /* the same process cannot be attached many times */

                if (child->flags & PF_PTRACED)

                        return -EPERM;

                child->flags |= PF_PTRACED;

                if (child->p_pptr != current) {

                        REMOVE_LINKS(child);

                        child->p_pptr = current;

                        SET_LINKS(child);

                }

                send_sig(SIGSTOP, child, 1);

                return 0;

        }

        if (!(child->flags & PF_PTRACED))

                return -ESRCH;

        if (child->state != TASK_STOPPED) {

                if (request != PTRACE_KILL)

                        return -ESRCH;

        }

        if (child->p_pptr != current)

                return -ESRCH;

        switch (request) {

        /* when I and D space are separate, these will need to be fixed. */

                case PTRACE_PEEKTEXT: /* read word at location addr. */

                case PTRACE_PEEKDATA: {

                        unsigned long tmp;

                        int res;

                        res = read_long(child, addr, &tmp);

                        if (res < 0)

                                return res;

                        res = verify_area(VERIFY_WRITE, (void *) data, sizeof(long));

                        if (!res)

                                put_fs_long(tmp,(unsigned long *) data);

                        return res;

                }

        /* read the word at location addr in the USER area. */

                case PTRACE_PEEKUSR: {

                        unsigned long tmp;

                        int res;

                        if ((addr & 3) || addr < 0

                            || addr > sizeof(struct user) - 3)

                                return -EIO;

                        res = verify_area(VERIFY_WRITE, (void *) data, sizeof(long));

                        if (res)

                                return res;

                        tmp = 0;  /* Default return condition */

                        if(addr < 17*sizeof(long))

                                tmp = getreg(child, addr);

                        else if(addr >= (long) &dummy->u_debugreg[0]

                                && addr <= (long) &dummy->u_debugreg[7])

                        {

                                addr -= (long) &dummy->u_debugreg[0];

                                addr = addr >> 2;

                                tmp = child->debugreg[addr];

                        }

                        put_fs_long(tmp,(unsigned long *) data);

                        return 0;

                }

      /* when I and D space are separate, this will have to be fixed. */

                case PTRACE_POKETEXT: /* write the word at location addr. */

                case PTRACE_POKEDATA:

                        return write_long(child,addr,data);

                case PTRACE_POKEUSR: /* write the word at location addr in the USER area */

                        if ((addr & 3) || addr < 0

                            || addr > sizeof(struct user) - 3)

                                return -EIO;

                        if(addr < 17*sizeof(long))

                                return putreg(child, addr, data);

                  /* We need to be very careful here.  We implicitly

                     want to modify a portion of the task_struct, and we

                     have to be selective about what portions we allow someone

                     to modify. */

                  if(addr >= (long) &dummy->u_debugreg[0] &&

                     addr <= (long) &dummy->u_debugreg[7]){

                          if(addr == (long) &dummy->u_debugreg[4]) return -EIO;

                          if(addr == (long) &dummy->u_debugreg[5]) return -EIO;

                          if(addr < (long) &dummy->u_debugreg[4] &&

                             ((unsigned long) data) >= 0xbffffffd) return -EIO;

                          if(addr == (long) &dummy->u_debugreg[7]) {

                                  data &= ~DR_CONTROL_RESERVED;

                                  for(i=0; i<4; i++)

                                          if ((0x5f54 >> ((data >> (16 + 4*i)) & 0xf)) & 1)

                                                  return -EIO;

                          };

                          addr -= (long) &dummy->u_debugreg;

                          addr = addr >> 2;

                          child->debugreg[addr] = data;

                          return 0;

                  };

                  return -EIO;

                case PTRACE_SYSCALL: /* continue and stop at next (return from) syscall */

                case PTRACE_CONT: { /* restart after signal. */

                        long tmp;

                        if ((unsigned long) data > NSIG)

                                return -EIO;

                        if (request == PTRACE_SYSCALL)

                                child->flags |= PF_TRACESYS;

                        else

                                child->flags &= ~PF_TRACESYS;

                        child->exit_code = data;

                        wake_up_process(child);

        /* make sure the single step bit is not set. */

                        tmp = get_stack_long(child, sizeof(long)*EFL-MAGICNUMBER) & ~TRAP_FLAG;

                        put_stack_long(child, sizeof(long)*EFL-MAGICNUMBER,tmp);

                        return 0;

                }

/*

 * make the child exit.  Best I can do is send it a sigkill.

 * perhaps it should be put in the status that it wants to

 * exit.

 */

                case PTRACE_KILL: {

                        long tmp;

                        if (child->state == TASK_ZOMBIE)        /* already dead */

                                return 0;

                        wake_up_process(child);

                        child->exit_code = SIGKILL;

        /* make sure the single step bit is not set. */

                        tmp = get_stack_long(child, sizeof(long)*EFL-MAGICNUMBER) & ~TRAP_FLAG;

                        put_stack_long(child, sizeof(long)*EFL-MAGICNUMBER,tmp);

                        return 0;

                }

                case PTRACE_SINGLESTEP: {  /* set the trap flag. */

                        long tmp;

                        if ((unsigned long) data > NSIG)

                                return -EIO;

                        child->flags &= ~PF_TRACESYS;

                        tmp = get_stack_long(child, sizeof(long)*EFL-MAGICNUMBER) | TRAP_FLAG;

                        put_stack_long(child, sizeof(long)*EFL-MAGICNUMBER,tmp);

                        wake_up_process(child);

                        child->exit_code = data;

        /* give it a chance to run. */

                        return 0;

                }

                case PTRACE_DETACH: { /* detach a process that was attached. */

                        long tmp;

                        if ((unsigned long) data > NSIG)

                                return -EIO;

                        child->flags &= ~(PF_PTRACED|PF_TRACESYS);

                        wake_up_process(child);

                        child->exit_code = data;

                        REMOVE_LINKS(child);

                        child->p_pptr = child->p_opptr;

                        SET_LINKS(child);

                        /* make sure the single step bit is not set. */

                        tmp = get_stack_long(child, sizeof(long)*EFL-MAGICNUMBER) & ~TRAP_FLAG;

                        put_stack_long(child, sizeof(long)*EFL-MAGICNUMBER,tmp);

                        return 0;

                }

                case PTRACE_GETREGS: { /* Get all gp regs from the child. */

#ifdef CONFIG_MATH_EMULATION

                        if (!hard_math)

                                /* Not supported. */

                                return -EIO;

#endif